Patent GB-653649-A (GB)
Title: Magnetic transducing apparatus
IPC: G11B15/43
Filed: 1948-03-08
Abstract: 653,649. Magnetic recording and reproducing apparatus. BRUSH DEVELOPMENT CO. March 8, 1948, No. 7110. Convention date, March 7, 1947. [Class 40 (ii)] In a magnetic sound-recording and-reproducing apparatus for steel wire or tape, means are provided to interrupt the drive when a desired amount of the medium has been removed from the supply reel, comprising a feeler lever or similar member mounted on the reel shaft, or on the reel itself, and operating through an aperture in the reel in such a manner that when the desired amount of the medium has been removed the said feeler member is tripped and causes the circuit of the driving motor to be interrupted. Fig. 1 shows one form of construction in which the medium passes between reels 20, 21. During recording or reproducing the medium 31 is drawn, by means of a constant-speed shaft 32 driven by a motor 203, from the supply reel 20 over the erazing head 27 and transducer 29, the take-up reel 21 being driven separately by means of a motor 291, a slipping belt 293 and a friction clutch-ring 271. During reproducing, rollers 208 and 205 press the medium 31 against the transducer 29 and drive-shaft 32, respectively, under the control of a push-rod 212. During recording the roller 209 presses the medium 31 also against the erazing head 27, under the control of a push-rod 214. The pushrods 212, 214 are retained in their operative positions, against the action of springs 216, by a spring-loaded latch bar 217. Any of the pushrods 211 to 214 may be released at any time by the operation of a push-rod 215 marked "Stop." Similarly, any of the push-rods 211 to 215 may also be released by operation of any other one of them. During a forward operation the friction clutch-ring 271 on the shaft 52 carrying the reel 20 is rendered inoperative by means of the spring-loaded slide 275. When, during a forward operation, a point near the end of the medium 31 is reached, the end 60 of a feeler lever 267, pivotally mounted on the cup 262, enters a slot 45 in the side of the reel 20 so that the outer end 283 of the lever 267 trips a lever 287 which releases the latch bar 217 and the push-rods 212, 214, thereby breaking the circuits of the motors 203, 291. During rewinding the friction-ring 271 on reel 20 is rendered operative and the friction-ring on reel 21 rendered inoperative. A feeler lever 267 is also provided on reel 21 which becomes operative to trip a lever 288 to stop a rewinding operation, a sloping edge 284 being provided on the lever 267 on the reel 20 to prevent the tripping of lever 287 at the start of a rewinding operation. A similar sloping edge is provided on the lever 267 on the reel 21 to prevent the lever 288 being tripped at the start of a forward operation. The constant speed shaft 32 is fitted with a fly-wheel 91 and is coupled to the shaft of the motor 203 by a length of rubber tubing 109, Fig. 8 (not shown), to damp out flutter and vibration from the motor. During "Fast Forward" and "Rewind" operations, under the respective control of push-rods 211 and 213, the rollers 205, 208, 209 are not pressed into engagement with the medium 31, which is thereby permitted to travel at a speed determined by that of the motor 291. In a modified construction, Fig. 2, the feeler lever 367 is cranked so that the inner end 366 presses outwardly against the innermost convolution of the medium 31. In another construction, Figs. 10 and 12, the feeler lever takes the form of a plate 6-21 which is pivoted at a point 6-22 on the side 6-15 of the reel, and is biassed outwardly by a spring 6-28 to the chain dotted position 6-21-T, where it may strike a bar 6-31 by which means the drive is interrupted. Other modified forms of the above feeler levers are described with reference to Figs. 4, 6 and 7 (not shown). Specification 647,962 is referred to.